Is there any limit on PLLA frequency when using the video generator, or will it work all the way up to 128MHz?
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cgracey

03-20-2009, 10:48 PM

128MHz is no problem for the video generator.

Feeding it data that fast·is the harder part.

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Chip Gracey
Parallax, Inc.

Cluso99

03-21-2009, 12:00 AM

Chip: I am presuming by your answer, we can run the prop up to 128MHz.
If so, is it ok to use 8MHz xtal and PLLx16 or do we need to use a 16MHz xtal and PLLx8? Is there anything else we should be aware of if using these speeds?

Chip is referring to the video generator and cog counters only. There is a separate PLL for this use and it and the counters can run much faster than the chip as a whole. You can run the Propeller's system clock at 128MHz if you're willing to refrigerate the chip. See the graph in section 10.2 of the Propeller datasheet.

Cluso99

03-21-2009, 01:18 AM

Thanks Mike. I haven't played with the video generator or counters, so I thought I must have missed something.